Brought down drone that's exhausted (7)
I believe the answer is:
humbled
'brought down' is the definition.
(thesaurus)
'drone that's exhausted' is the wordplay.
'drone' becomes 'hum' (I've seen this before).
'that's exhausted' becomes 'bled' (to exhaust something might be to bleed it dry).
'hum'+'bled'='HUMBLED'
(Other definitions for humbled that I've seen before include "Crushed" , "Brought low" .)